// 间距
$spacer     : 16px;
$spacers : (
    0: 0,
    1: ($spacer * .25),
    2: ($spacer * .5),
    3: ($spacer * .75),
    4: ($spacer * 1),
    5: ($spacer * 1.5),
    6: ($spacer * 2),
    7: ($spacer * 3),
);
@each $prop, $abbrev in (margin: m, padding: p) {
  @each $size, $length in $spacers {
    .#{$abbrev}-#{$size} { #{$prop}: $length !important; }
    .#{$abbrev}t-#{$size},
    .#{$abbrev}y-#{$size} {
      #{$prop}-top: $length !important;
    }
    .#{$abbrev}r-#{$size},
    .#{$abbrev}x-#{$size} {
      #{$prop}-right: $length !important;
    }
    .#{$abbrev}b-#{$size},
    .#{$abbrev}y-#{$size} {
      #{$prop}-bottom: $length !important;
    }
    .#{$abbrev}l-#{$size},
    .#{$abbrev}x-#{$size} {
      #{$prop}-left: $length !important;
    }
  }
}